Vacuum bag processing may be used to form composite parts, typically curing within an oven or an autoclave. For example, vacuum bagging is a common step in resin transfer molding and wet layup molding. In wet layup molding, the uncured composite part is placed, typically one layer at a time, on a base, such as a tool or lay-up mandrel, and covered by a vacuum bag, which is then sealed to the base using an adhesive sealant, typically a vacuum bag sealant tape. The sealed bag forms a vacuum tight enclosure which is evacuated during cure of the composite part.
In addition to the seal of the vacuum bag to the base, which forms a sealed seam around the composite part, vacuum bag processing may also involve other seams which need to be sealed. For example, large parts may be larger than convenient sizes of vacuum bag film. Also, parts with non-flat configurations (e.g., high aspect ratios, three-dimensional curves, and/or significant surface protrusions) may require seams and/or pleats to accommodate the part geometry.
Conventional seaming is performed one of two ways. The most common way is the use of vacuum bag sealant tape (e.g., TACKY TAPE brand butyl sealant tape). This is a semi-cured elastomeric material which is extremely tacky and easily bonds to common vacuum bag films. Typically, an operator manually smooths the seam and sealant to close any leak paths which can be very time consuming, arduous, and tedious. The second method to seam vacuum bags is heat seaming, which thermally welds two bags together. Currently, this technique is usually only performed by a manufacturer of vacuum bags prior to shipping to the user, and only in sections where the two bags can be laid flat upon each other. In any vacuum bag process, vacuum integrity is essential to produce high quality composites consistently. Accordingly, there is a need for apparatuses and methods for efficient sealing of vacuum bag seams.